Release Note: `sun.misc.Unsafe.shouldBeInitialized` and `ensureClassInitialized` Are Removed

The `shouldBeInitialized(Class)` and `ensureClassInitialized(Class)` methods have been removed from `sun.misc.Unsafe`. These methods have been deprecated for removal since JDK 15. `java.lang.invoke.MethodHandles.Lookup.ensureInitialized(Class)` was added in Java 15 as a standard API to ensure that an accessible class is initialized.